The Mexican-United States barrier also known as the border wall is a series of vertical barrier along the mexico-united states border intended to reduce illegal immigration to the United States from Mexico. The barriers were built from 1994, by Bill Clinton, as part of three larger operations to taper transportation of illegal drugs manufactured in Latin America and illegal immigration:

Throughout his 2016 presidential campaign, Donald Trump called for the construction of a much larger and fortified border wall, claiming that if elected, he would build the wall and make Mexico pay for it. More than $1.5 billion of border wall funding has produced 1.7 miles of fencing along the nation’s southern border. The border wall is not really proving effective as their are large gaps not blocked where illegal migrants could get through.
In my opinion Donald Trump is stupid, he has wasted so much money and still there are illegal migrants getting through the border wall. The wall has recently increased the amount of illegal migrants getting through to the USA.
